The present invention relates to a tyer for tying stacks of articles. In particular, the present invention relates to a tyer for stacks of printed publications such as newspapers which are stacked into either tall stacks (logs) or short stacks (bundles).
Stacks formed in a newspaper stacker have been tied by automatic tying devices. Such devices include means for compressing the stack, a tie head, and a track or chute around a stack of newspapers. The tie head feeds the strap through the track around the compressed stack, tightens the strap, cuts the strap and fastens the ends together. Because the tie head fastens the ends of the tightened strap together, the tie head must be located immediately adjacent one surface of the stack. Machines capable of tying a strap around a stack or other articles are manufactured by Signode Corporation, 2600 N. Western Avenue, Chicago, Ill. 60647.
Prior automatic tyers have been limited in the size of stacks they can tie by the circumference of the track which guides the strap. Newspaper sections, in particular, have been tied in short stacks (bundles) about 12-14 inches high. Tying of publications in tall stacks (logs) up to about 40 inches high has generally been limited to tying signatures for books or magazines. Obviously, an automatic tyer cannot tie a stack too large to fit within the perimeter of the track through which the strap is fed. While it is possible to tie a relatively short stack (a bundle) in a tyer with the capacity to tie a tall stack (a log), the time required to tie such a short stack is unnecessarily long because the strap must be fed through a track with a perimeter much larger than the perimeter of the short stack and then the slack removed. The time required to feed the extra strap and then remove the slack is wasted, and extends the total cycle time for tying bundles. For these reasons, no single prior tyer could efficiently tie both bundles and logs.
In the past, when logs of signatures have been stacked and tied, end boards have been used. The end boards prevented "butterflying" of the ends of the stack when a strap was tightened around the middle of the compressed stack. A bottom end board was placed manually on the stacking platform in an automatic stacker prior to the arrival of the first article to be stacked. When a preselected number of articles had been stacked, a top end board was placed on the stack and the stack complete with end boards was moved to a tyer. When the stack was ready for use, the strap was cut and the end boards were returned to the stacker for reuse.